A cross-reactive array sensor is a device that mimics the sense of smell in mammals. It is generally thought that mammal's sense of smell, which is called olfaction, operates by the brain interpreting a complex patterned response from the olfactory bulb where odors interact with between 800-1200 different receptors. Each receptor in the olfactory bulb is slightly different so that when they all interact with the same odor they all respond slightly different making a pattern that is characteristic of that odor. Due the different chemical nature of each odor the olfactory bulb makes a unique pattern for each odor that is able to be distinguished.
Cross-reactive arrays mimic the sense of smell by using more than one broadly responsive (non-specific) chemical sensor to generate a patterned response which is then interpreted by a computer algorithm to identify the chemical being interrogated. These have been made using many different sensing methods including tin oxide sensors, carbon black polymer composites, fluorescent polymers, carbon nanotubes, inorganic dyes, quantum dots, functionalized metallic nanoparticles, and others. A few good references on these type of devices are, e.g., Anzenbacher, Jr., P., Lubal, P., Buček, P., Palacios, M. A. & Kozelkova, M. E. A practical approach to optical cross-reactive sensor arrays. Chem. Soc. Rev. 39, 3954 (2010); and Albert, K. J. et al. Cross-Reactive Chemical Sensor Arrays. Chem. Rev. 100, 2595-2626 (2000).
All of the previous examples of cross-reactive arrays placed the sensing elements on the same plane where they interact with the sample. Additionally, all cross-reactive arrays are poor at identifying components in a mixture sample. This invention is similar but different than U.S. Pat. No. 7,189,353 B2. U.S. Pat. No. 7,189,353, entitled, “Use of spatiotemporal response behavior in sensor arrays to detect analytes in fluids,” discloses a time delay feature added to the feature vector for added discrimination ability and components in a mixture can theoretically be discriminated.
Other references worth mentioning are Cross-reactive sensors, U.S. Pat. No. 7,250,267 B2 issued to Walt et al.; and Method for determining analyte concentration by cross-reactivity profiling, U.S. Pat. No. 5,338,659 A issued to Kauvar et al.